'use client';

import { useEffect } from 'react';

import { getAuthInfoFromBrowserCookie } from '@/lib/auth';

/**
 * Token 自动刷新管理器
 *
 * 功能：
 * 1. 拦截所有 fetch 请求
 * 2. 检测到 401 错误时自动刷新 Token 并重试
 * 3. 在请求前检查 Token 是否即将过期，主动刷新
 *
 * 策略：
 * - 响应拦截：401 错误 → 刷新 Token → 重试请求
 * - 请求拦截：剩余时间 < 10 分钟 → 主动刷新
 */
export function TokenRefreshManager() {
  useEffect(() => {
    // localStorage 模式不需要刷新
    const storageType = (window as any).RUNTIME_CONFIG?.STORAGE_TYPE || 'localstorage';
    if (storageType === 'localstorage') {
      return;
    }

    // 刷新状态管理
    let isRefreshing = false;
    let refreshPromise: Promise<boolean> | null = null;

    // Token 刷新函数
    const refreshToken = async (): Promise<boolean> => {
      // 如果正在刷新，返回现有的 Promise
      if (isRefreshing && refreshPromise) {
        return refreshPromise;
      }

      isRefreshing = true;
      refreshPromise = (async () => {
        try {
          // 使用原始 fetch 避免递归
          const response = await window.fetch('/api/auth/refresh', {
            method: 'POST',
            credentials: 'include',
          });

          if (response.ok) {
            console.log('[Token] Refreshed successfully');
            return true;
          } else {
            console.error('[Token] Refresh failed:', response.status);

            // 刷新失败，跳转登录
            if (response.status === 401 || response.status === 403) {
              window.location.href = `/login?redirect=${encodeURIComponent(window.location.pathname + window.location.search)}`;
            }
            return false;
          }
        } catch (error) {
          console.error('[Token] Refresh error:', error);
          return false;
        } finally {
          isRefreshing = false;
          refreshPromise = null;
        }
      })();

      return refreshPromise;
    };

    // 检查 Token 是否需要刷新
    const shouldRefreshToken = (): boolean => {
      const authInfo = getAuthInfoFromBrowserCookie();
      if (!authInfo || !authInfo.timestamp || !authInfo.refreshExpires) {
        return false;
      }

      const now = Date.now();

      // Refresh Token 已过期
      if (now >= authInfo.refreshExpires) {
        console.log('[Token] Refresh token expired, redirecting to login');
        window.location.href = `/login?redirect=${encodeURIComponent(window.location.pathname + window.location.search)}`;
        return false;
      }

      // 计算 Access Token 剩余时间
      const ACCESS_TOKEN_AGE = 4 * 60 * 60 * 1000; // 4 小时
      const age = now - authInfo.timestamp;
      const remaining = ACCESS_TOKEN_AGE - age;

      // 剩余时间 < 10 分钟时需要刷新
      const REFRESH_THRESHOLD = 10 * 60 * 1000; // 10 分钟
      return remaining < REFRESH_THRESHOLD && remaining > 0;
    };

    // 保存原始 fetch
    const originalFetch = window.fetch;

    // 拦截 fetch
    window.fetch = async (input: RequestInfo | URL, init?: RequestInit): Promise<Response> => {
      // 跳过刷新 API 本身
      const url = typeof input === 'string' ? input : input instanceof URL ? input.href : input.url;

      if (url.includes('/api/auth/refresh')) {
        return originalFetch(input, init);
      }

      // 请求前检查：Token 即将过期时主动刷新
      if (shouldRefreshToken() && !isRefreshing) {
        console.log('[Token] Expiring soon, refreshing proactively...');
        await refreshToken();
      }

      // 发送请求
      let response = await originalFetch(input, init);

      // 响应拦截：401 错误时刷新 Token 并重试
      if (response.status === 401 && !isRefreshing) {
        console.log('[Token] Received 401, attempting refresh and retry...');

        const refreshed = await refreshToken();

        if (refreshed) {
          // 刷新成功，重试原请求
          response = await originalFetch(input, init);
        }
      }

      return response;
    };

    // 清理：恢复原始 fetch
    return () => {
      window.fetch = originalFetch;
    };
  }, []);

  // 这是一个纯逻辑组件，不渲染任何内容
  return null;
}